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APPENDIX A. (LONSDALE ON CORALS.) 
about three inches square on the upper surface, and one and a half in thickness at the outer edge, the 
lower surface being very uneven. The columns in general diverged slightly. Their form was very 
irregular, the relative dimensions in the sides of even the fully-developed being often extremely unequal. 
The diameter of the more regular, which had attained this state, averaged two and a half lines. 
In an endeavour to trace the mode of production of the young columns and their progress towards ma- 
turity, it is necessary to premise, that no instance was observed in the series of exposed transverse sec- 
tions of a line indicating a fissiparous process, or of such an irregularity among the lamell® as would arise 
from the development of germs. The earliest signs of young columns existed in the occurrence of small 
intervals, irregular in form, but surrounded by facets of adjacent columns as perfect in their boundary struc- 
ture as were the facets of the other sides adjacent to which no intervals appeared (fig. 1,1a). The outline 
of these spaces was generally more or less curved, producing convexities in the planes of the adjacent 
columns, and where it was three-sided it resembled a spherical triangle. This character is conceived to 
be of importance ; for if the curvature had existed uniformly only on the facet of one of the older columns, 
it might have indicated a fissiparous separation from that column. It is believed, however, that the 
curves may be considered to have resulted from the struggles of the young polype on all sides for room ; 
and that it was therefore called into existence while the older polypes were constructing their tubes, and 
had not given them a sufficient solidity to resist the outer pressure. 
In the next state the intervals (which apparently arose from a decay of feebly-constructed solid parts) 
were occupied by lamelliferous tubes (fig. 1, 1 a), agreeing perfectly in character with the mature columns, 
except that the number of lamellae was much smaller, and that the sides were considerably curved. Be- 
tween this state and the fully-developed no other changes necessarily appeared than an increase in the 
number of the lamellae and a tendency to produce, for the greater part, straight walls. 
A perfect vertical exterior of the columns was not exposed, but in transverse sections a nearly even 
line traversed the middle of the comparatively thick opake layer, which intervened between the adjacent 
stellated lamellae (fig. 1 a) ; proving clearly, that the walls were separable, and resulted from the labours 
of individual polypes. The outer characters so excellently given in Prof. Goldfuss’s figures, 9 a to 9 c, 
plate 24. (Petref.), were also well exhibited in weathered or decayed portions, and clearly shown to be 
due to the removal of the exterior and the preservation of the arched union of pairs of the lamellae. 
The only perfect terminal cups which were preserved, were seated below the surface and within the 
specimen, having belonged to polypes prematurely killed, and overarched by the lateral extension of other 
columns. They were deep and elliptical in outline (figs. 1 b, 1 c), and totally unlike those of the coral 
represented in plate 19, fig. 1 a of the ‘ Petrefacta Musei Bonnensis.’ They were lined by regularly 
curved, slightly projecting lamella;, the alternate narrower plates descending also nearly to the bottom. 
No central boss was exhibited. 
Locality and Formation. — Habsal, near Reval. Lower Silurian. 
Lituostrotion, Lhwyd. 
This name was originally proposed by Lhwyd (Ichnographia, 1699) for a coral figured in the 23rd 
plate of his work, and designated “ Lithostrotion sive Basaltes minimus striatus et stellatus. It was 
apparently first adopted as a systematic generic appellation by Dr. Fleming, in his ‘ History of British 
Animals’ (p. 508, 1828); and it has been subsequently retained by other authorities, but without any 
great precision, respecting essential characters. In a notice on a genus lor which the designation of 
Stylastreea is suggested, will be found reasons for concluding, that Lliwyd’s fossil ( Lithost . striatum ? 
Brit. Anim. p. 508) possesses characters so perfectly different from those of Dr. Fleming’s Lithost. flori- 
forme, as to render the establishment of a distinct genus necessary. At first it appeared advisable to 
